Apparatus for demonstrating sound-absorbing properties



SEARCH RGOM June 24, i930. c. F. suman;

5 I APPARA-TUS FOR DEMONSTRATING SOUND ABSORBING PROP' 2 Sheets-Sheet 1 June 24, 1930. c. F. BURGESS APPARATUS FOR DEHONSTRATI-NG SOUND BSORBING PROPERTIES Filed June 19, 1929 2 Sheets-Sheet 2 jez/elder C72/ares Dllll lllllll) "fgoriji'ran STATES PATENT ovrri Patented June 24, 1930 OF BOXEELIA,

FLORIDA, Assienon To c. r. Boneless monaoF MADISONLWISCONSIN, A CORrORATroN or DELAWARE APPARATUS ros. DEMQNSTRATING soUNn-ABsoismornoPEnmiEs r Application :tiled .T une 19,

This invention relates to improvements in materials in tubular apparatus for demonstrating the sound-absorbing properties of various materials and constructions.

One object of the invention is to provide a compact portable apparatus which may be used t0 demonstrate readily and audibl)v the sound-absorbing properties of various soundabsorbing materials and facing materials.

Other objects relate to various features of construction and arrangement of parts which will be apparent from the consideration of the following specification and accompanying drawings wherein, e

Fig. l is a longitudinal cross-sectional elevation of one embodiment of my improvements, the section being taken along the line 1-1 of Fig. 2.

Fig. 2 is a. transverse sectional elevation taken along the line 2 2 of Fig. 1.

Figs. 3 and t illustrate two types of facing form which may be used in conjunction with different soundabsorbing materials.

Fig. 5 is a side elevation of a sound absorbing cylinder.

n acoustical construction work it frcqucntly is desirable to demonstrate soundabsorbing qualities of various kinds 0f acoustical construction in sounti-absorbing materials to those unfamiliar with acoustical correction problems so that they may 4judge 0f the comparative qualities o such materials and constructions. A device for this purpose should be compact so that it may be transported conveniently and should be so constructed that various acoustical c0nstructions and sound-absorbing materials may be demonstrated quickly so that a. comparison of their sound absorbing qualities can be perceived.

In the drawings, 10 is an outer casinf.,7 which in the form shown in Fig. 1 is open at its left hand end and at its right hand end is provided with a wall 11. A transverse partition 12 divides the casing interior into compartments 13 and 14. Positioned within compartment 1-1is a box 15, preferably of metal, having mounted therein a sound-emitting device, such as an electric 192s. serial No. 372,013.

box is filled with sound-absorbing material 19 which may be felted wood fiber known as balsam-wool or hair-felt or the like, which should be of sufficient. thickness and so compacted that it will not transmit the vibrations or sound set up by the sound-emittin device to the outer case 10, and whereby the sound or vibrations will pass through the tube 2O which forms e. sound-passage from the chamber in which the bell is located to the chamber 13.

lSecured to the walls 11 and 12, as by soldering or welding or other approved c0nstruction, are tubes 21, 22, 23, and 24. Tube 2l is arranged conccntrically with the axis of the passage 2f), as shown in Fig. 1. The wall 1l is apex-lured at the out-er ends of the tubes 20-24, inclusive.

In conjunction with the apparatus shown there may be prepared a. number of cylinders of dillerent sound-absorbing qualities, for demonstration purposes. In ig. 1 a cylinder 25 is shown, whichmay be of plaster or plaster-like material, and provided with a central longitudinal passage 26 therethrough which registers with the tube 20. The cylinder 25 may be enclosed in a protecting metal sheath 27, which sheath preferably extends over one end of the cylinder as shown at 28, the end of the sheath havinfr a central opening in registration with the passage 26.

As will be apparent, when the bell or an equivalent device is operated, the sound will pass through thc tube 20 into the passage 26 of the cylinder 25, and the sound-absorbing characteristics of the material of which the cylinder is made may be detected by an acoustimeter, or by the ear. The cylinder :25 can readily be withdrawn from the supportingr tube 21 and another cylinder, formed of t ingr material, may be inserted for the purpose of comparison. For instance, a second Cylinder 29, having a central opening 30 may be formed of balsam-wool, hair felt, or other illerent sound-absorb- -ivhile the apparatus is beingcarried.

material having recognized sound-absorbing qualities and may be withdrawn from the storage tube 22 and placed in the testin tube 21. By operating the bell or other evice 16, the sound-absorbing quality of said material can be demonstrated.

Lily device is especially-,useful for testing facings for sound-absorbing materials. For this purpose a tube or cylinder 23' 1s made of the facing material which it is `desired to test, such as perforated metal, as shown in Fig. 3. Said cylinder may be slipped into duct 30 in alignment with tube 20, to serve as a facing for soundabsorbing material 29. An imperoratef'metal tube 24' is shown in Fig. 4. The tubes or cylinders are readily replaceable and interchangeable s o that they may be tested in rapid order, and they mav be stored in the storage tubes 23, 24. Thb

entire sound-absorbing construction also may be removed as a unit and another may be inserted.

It, `.vill be understood that any number of cylinders formed of diierent sound-absorbing materials may be employed and additional tubes of different facing materials may likewise be used for making comparison. lTith the device shown, the listener hears practically only that sound which emerges from the duct 26 or 30, as the case may te, which is a continuation of duet 2O since the sound-absorbing and vibration-ab` sorbing construction used prevents practically any sound or vibrations'from passing through the Walls ofthe device to the listener. If desirable, the bell may be replaced by a sound-emitting device in which the intensity, quality and tone may be controlled.

The casing l0 is preferably provided with an end cover 31, which may be hinged at 32 and provided with any suitable fastening means 33 for holding the cylinders in place ll'here a. larger number of cylinders of sound-ab` sorbing materials or of facing materials is desired to be carried, the casing may be enlarged to provide space for the necessary storage tubes.

Although l have shown and described a certain embodiment of the present invention for the purpose of illustration, it will be seen that varius changes may be made therein without departing from the spirit of the invention as defined in the appended claims.

lVliat I claim is:

Apparatus of the class described, com` prismg a vibration absorbing construction, a controllable sound generating device therein, a duct for conveying sound from said deyice and a member to be demonstrated havmg a passage therethrough in communica tion with said duct.

QAn acoustic demonstration device cornprismg in combination a'vibration absorbing construction, a controllable source of sound encased therein, a duct for conveying sound from said source,

and an independent.

unit comprising a second duct communicat- `Apparatus of the eliiss described coin-1` prising a vibration absorbing chamber, a controllable sound generating device therein, a duct for conveying sound from said device, and a plurality o members having longitudinal passages therein adapted to be placed in communication singly with said duct, the Walls of said passages being formed of material to be demonstrated.

4. An acoustic demonstration device coinprising in combination a vibration absorbing construction, a controllable source of sound encased therein, a sound outlet duct therefor a second duct member having a sound-absorbing wall and interchangeable acings for said absorbing Wall forming extensions of said lirst duct.

5. Acoustic demonstration apparatus comprising a vibration absorbing construction, a controllable sound generating device there` in, a duct for conveying sound from said device, a member having a. passage therethrough adapted to be placed in communication with said duct, the Wall of said passage being formed of sound absorbing material, and interchangeable facing members adapted to be inserted singly in said passages.

G. Apparatus of the class described corupris-ing a casing having an apertured end wall, a transverse partition in said casing defining two chambers, vibration absorbing material in one chamber, a controllable sound generating device encased Within said material, said device to said other chamber, supporting means disposed between said partition and said end wall, and a member having a longitudinal passage therethrough slidable into said second chamber through the aperture in said end wall, said member being guided by said supporting means for effecting the registration of said passage with said duct. I i

7. An acoustic demonstration device com.- prising a casing having a transverse apertured partition therein defining two cham-- bers, vibration absorbing material in one chamber, a controllable sound emitting device encased Within said material, a duct for conveying sound from said device through the aperture of said partition, said casing having an end wall provided with a plurality of openings, one of said openings being aligned with the aperture in said partition. supporting members in said second chamber each extending from adjacent one of said openings in said end wall to said partition and demonstration members having longia duct for. conveying sound from carried by said supporting members, each of Asaid demonstration members being adapta! to be inserted through the opening aligned y the longtuinal aswith said duct where sagi'sl thereof forms an extension cf the uct testimony whereof, I' have subscn my name.

CHARLES F. BURGESS. 

